Compare Fiberglass vs Aluminum Windows


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Fiberglass vs Aluminum Windows

If you are comparing fiberglass vs. aluminum windows, here are four important areas to constrast before buying. See our window cost estimator for more pricing specifics.


Aluminum windows are generally considered the strongest and most durable of all window frames. This is the primary reason that they are a good choice for hot desert climates - the material won't bend and warp like a poorly made vinyl extrusion can. However, fiberglass is very strong as well, certainly strong enough for 99% of all residential homes. These two materials top the list from a strength and druability point of view and either one is a great choice (if these options fall within your budget).


Aluminum frames have their own style and look to them - specifically a more modern or commercial look and feel. They generally have thinner frames because they are so strong, which allows for more glass area and a more open, sleek appearance. Fiberglass windows are more of a mixed bag, they tend to look almost indistinguishable from vinyl windows, although because they are stronger than most vinyl frames, they can be thinnner. Generally, they are a little thicker than aluminum and come in a variety of colors and finishes, where aluminum tends to offer less color options.

Energy Efficiency

Poor energy efficiency is the big knock on aluminum and the primary reason why many homeowners opt for another type of frame material. Most aluminum windows are actually much more energy efficient than older ones because they are thermally broken. However, they still lag behind most other materials in terms of performance numbers. Fiberglass, on the other hand, is quite energy efficient and well made models and window series offer some of the best performance numbers out there. There tends to be debate amongst contractors and other industry experts as to whether high end fiberglass or high end vinyl windows offer the best numbers, but fiberglass certainly tops aluminum in this category.

Cost & Value

Both of these options will be more expensive than a comparable vinyl frame and a bit less than a wood clad frame. (It should be noted that most wood clad frames use an aluminum or a fiberglass as the exterior cladding material.) Each of these offers good long term value, given a quality manufacturer and installation. Expect a mid range aluminum or fiberglass window to run $550 to $650 installed for a typical sized double hung window. The Marvin Infinity and Integrity are two highly regarded fiberglass frames - check Marvin windows prices for cost breakdowns and analysis on these two options.

Bottom Line

Aluminum is best left to very warm climates or for homeowners that love the overall commercial or modern look of this material. Fiberglass composites are great options for any homeowner that wants a quality window and can afford the price. Not all fiberglass windows are equal - check on what we feel are the best fiberglass windows available.

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